{"title":"Gradient Technique Theory: Tracing Magnetic Field and Obtaining Magnetic Field Strength","authors":"Alex Lazarian, Ka Ho Yuen and Dmitri Pogosyan","doi":"10.3847/1538-4357/ad6d62","DOIUrl":null,"url":null,"abstract":"The gradient technique is a promising tool with theoretical foundations based on the fundamental properties of MHD turbulence and turbulent reconnection. Its various incarnations use spectroscopic, synchrotron, and intensity data to trace the magnetic field and measure the media magnetization in terms of Alfvén Mach number. We provide an analytical theory of gradient measurements and quantify the effects of averaging gradients along the line of sight and over the plane of the sky. We derive analytical expressions that relate the properties of gradient distribution with the Alfvén Mach number MA. We show that these measurements can be combined with measures of sonic Mach number or line broadening to obtain the magnetic field strength. The corresponding technique has advantages to the Davis–Chandrasekhar–Fermi way of obtaining the magnetic field strength.","PeriodicalId":501813,"journal":{"name":"The Astrophysical Journal","volume":null,"pages":null},"PeriodicalIF":0.0000,"publicationDate":"2024-10-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"The Astrophysical Journal","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/10.3847/1538-4357/ad6d62","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}
引用次数: 0
Abstract
The gradient technique is a promising tool with theoretical foundations based on the fundamental properties of MHD turbulence and turbulent reconnection. Its various incarnations use spectroscopic, synchrotron, and intensity data to trace the magnetic field and measure the media magnetization in terms of Alfvén Mach number. We provide an analytical theory of gradient measurements and quantify the effects of averaging gradients along the line of sight and over the plane of the sky. We derive analytical expressions that relate the properties of gradient distribution with the Alfvén Mach number MA. We show that these measurements can be combined with measures of sonic Mach number or line broadening to obtain the magnetic field strength. The corresponding technique has advantages to the Davis–Chandrasekhar–Fermi way of obtaining the magnetic field strength.
梯度技术是一种很有前途的工具,其理论基础是 MHD 湍流和湍流重联的基本特性。它的各种化身利用光谱、同步辐射和强度数据来追踪磁场,并以阿尔弗文马赫数来测量介质磁化。我们提供了梯度测量的分析理论,并量化了沿视线和天空平面平均梯度的影响。我们推导出了梯度分布特性与阿尔弗文马赫数 MA 相关的分析表达式。我们表明,这些测量结果可以与声波马赫数或线展宽测量结果相结合,从而获得磁场强度。与戴维斯-钱德拉塞卡-费米(Davis-Chandrasekhar-Fermi)获取磁场强度的方法相比,相应的技术更具优势。